From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 18 Feb 2002 18:05:18 -0800 (PST) From: Linus Torvalds Subject: Re: [RFC] Page table sharing In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Rik van Riel Cc: Daniel Phillips , Hugh Dickins , dmccr@us.ibm.com, Kernel Mailing List , linux-mm@kvack.org, Robert Love , mingo@redhat.co, Andrew Morton , manfred@colorfullife.com, wli@holomorphy.com List-ID: On Mon, 18 Feb 2002, Rik van Riel wrote: > > The swapout code can remove a page from the page table > while another process is in the process of unsharing > the page table. Ok, I'll buy that. However, looking at that, the locking is not the real issue at all: When the swapper does a "ptep_get_and_clear()" on a shared pmd, it will end up having to not just synchronize with anybody doing unsharing, it will have to flush all the TLB's on all the mm's that might be implicated. Which implies that the swapper needs to look up all mm's some way anyway, so the locking gets solved that way. (Now, that's really pushing the problem somewhere else, and that "somewhere else" is actually a whole lot nastier than the original locking problem ever was, so I'm not claiming this actually solves anything. I'm just saying that the locking isn't the issue, and we actually have some quite fundamental problems here..) Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/